Principles of Radiotherapy in Head & Neck Surgery and Recent Advances by Dr. Aditya Tiwari.

1. Principles of
radiotherapy in head &
neck surgery

2. INTRODUCTION
• Head and neck cancer represents the 6th most
common malignancy & accounts for approx. 6% of
new cancer cases annually worldwide.
• Treating HNC is often complex
• Radiotherapy – definitive, adjuvant and recurrent
disease settings of HNC.
• Innovations will continue to improve outcomes by
minimizing toxicity and maximizing organ
preservation such as salivation, speech, and
swallowing, that are key factors in determining
quality of life after treatment through the use of

3. • The first patient was treated with radiation in 1896,
two months after the discovery of the X-ray.
• Back then, both doctors and non-physicians treated
cancer patients with radiation.
• Rapid technology advances began in the early 1950s
with cobalt units followed by linear accelerators a
few years later.
• Recent technology advances have made radiation
more effective and precise.
THE BRIEF HISTROY ABOUT
RT..

5. What is Radiotherapy ?....
• It is the medical use of ionizing radiation, generally as part of cancer
treatment to control or kill malignant cells by destroying reproductive
integrity of the malignant cells.
What is radiation?....
• Radiation refers to the propagation of energy through space or a
medium.
• If the radiant energy is carried off by a particle that has rest mass, the
radiation is particulate or corpuscular radiation; e.g.-electrons, β-
particles protons, neutrons, & heavy charged particles.
• Electromagnetic radiation is a packet of energy (a photon) that
propagates through space.
• It has no rest mass and propagates at the speed of light.
• This discrete energy (E) is related to its associated frequency (v) as
follows: E = hv where h is Planck’s constant, with a value of 6.626
× 1034 joulesecond (J-s).

6. Types of Radiation
1] Photon beam (X-ray, Gama –ray)
2] Electron beam
3] Particle radiation (Neutron ,proton, pions)

7. X ray photons
• X rays are produced when electrons decelerate.( hit against a target).
• Poor penetration.
• Effective depth – 1cm.
• Skin tumours.
• Exception-Megavoltage beams.
• Gamma rays are emmited by radioactive isotopes from excited
nucleus itself.
• Oldest – Radium., Caesium & cobalt.
• Cobalt is more widely used : Deep penetration. Low cost and
maintainance.
• Disadvantages: Not precise
Gamma rays are more harm to human body than the X- rays.
Gamma rays have shorter wavelengths than the X-rays.
Gamma rays

8. Electron beam
• The subject is directly bombarded with electrons.
Property :
• The depth of penetration of electron beam depends
on energy level of electron.
• Hence the beam has a depth limit.
Uses :
a) In head and neck Ca, where spinal cord is to be spared.
b) Primary skin tumour of pinna & cartilage of nose.
c) Anterior placed tumour of frontal & ethmoidal sinus (
electron beam for ant field, supervoltage for lateral field)

9. Proton beam
• Heavy positive charged particles.
• Advantages:
a) Depth dose distribution. Small entry & exit point.
b) Maximum dose is depth related- Bragg peak.
c) DOES NOT DEPEND ON TISSUE O2.
• Application:
a) Chondosarcoma of skull base.
b) Chondroma of clivus.
• Mechanism : Heavy energy machines produce heavy uncharged
paticles.
• Advantage : Cells need to be oxygenated to only 1.5 times(compared
to 3 times)
Neutrons

10. LINEAR ACCELRATOR (LINAC)
a) It is a type of particle accelerator that greatly increases the
kinetic energy of charged subatomic particles or ions by
subjecting the charged particles to a series of oscillating electric
potentials along a linear beamline.
b) A stream of electrons produced from a filament in an
electrically charged field is accelerated through a series of
wave guides in conjunction with a radiofrequency pulse to
within a fraction of the speed of light.
c) This electron beam can itself be used for treatment or can
impact on a target to produce a photon beam of maximum
energy between 4 and 20MV according to the design and
calibration of the machine.
d) Electron beams are useful for treating superficial lesions
because the maximum of dose deposition occurs near the

11. • USE:- They generate X-rays and high energy electrons for medicinal
purposes in radiation therapy, serve as particle injectors for higher-
energy accelerators, & are used directly to achieve the highest kinetic
energy for light particles (electrons and positrons) for particle physics.
• LIMITATIONS:- a) The device length limits the locations where one
may be placed. b)A great number of driver devices and their
associated power supplies are required, increasing the construction
and maintenance expense of this portion.

12. Radiotherapy can be given as
• External radiotherapy (EBRT or XRT or
Teletherapy)
• Internal radiotherapy (Brachytherapy or sealed
source radiation therapy, curietherapy or
endocurietherapy)
1] Interstitial implant
2] Intracavitary implant
o Systemic radioisotope therapy (or unsealed source
radiotherapy)
Used alone or in combination
with other therapies such as
surgery, EBRT & chemotherapy

13. RADIOBIOLOGY
A] Teletherapy (External Beam Radiation Therapy)
• Most widely used
• Often uses photon beams.
• Used to treat large areas of the body
• Usually given daily over several weeks.
• Therapeutic radiation is delivered by two main methods:
(1) Electromagnetic radiation (photons) X-rays and gamma
rays
(2) Particulate radiation in the form of electrons, neutrons, and
protons. Ionizing radiation deposits energy at a constant rate as it
travels through matter, defined as linear energy transfer (LET).
• “ 4 Rs” principle of RT: - 1) Repair of sublethal damage;
2) Redistribution across the cell cycle;
3) Repopulation; & 4) Reoxygenation.

14. • Each unit of absorbed radiation is called one gray (Gy)
Equivalent to one joule per kilogram of tissue.
• One Gy = 100 centiGy (cGy) or 100 rads. (The rad [radiation
absorbed dose] is the previous name for the absorbed dose unit.)
• The relative biological effectiveness (RBE) is a measure of the
ability of radiation with different LETs to produce the same
biological effect under the same conditions.
• A 250-kV x-ray beam generally is used as the reference source
for comparison.
• Beams of 4–6MV are most appropriate for the treatment of
HNC.
• The radiation is artificially produced by a LINEAR
ACCELERATOR.
• The energy of up to 30MeV & more can be 600-fold higher than
this of conventional x-ray machine.

15. Procedure:-
• Position:- Supine position MC  It is imp to achieve same alignment
each day.
• Simulation:- It is a T/t machine capable of planning a patient for RT,
but can’t give T/t i.e. process in which one tries to copy a procedure.
• Beam shaping:- Rectangular beams converted into irregular shapes to
shield normal tissue.
• Contour:- The method of transferring the patient across sectional
outline onto paper using wire, plastic, or CT scans.
• Beam characteristic:- Photon beams are routinely specified by % dose
depth Since photon energy α surface dose
• Portals:- Lateral parallel opposite portals are used to treat HNC.
• T/t volume:- It includes the tumor volume + 2-3 cm of surrounding
tissues (target volume) + an adequete margin of tissue to include
microscopic extention of the tumor.
• Dosimetry:- After the patient is simulated & the T/t portals are fixed,
the dose calculations is made using the T/t planning system.

16. • MECHANISM :- A stream of electrons produced from a
filament in an electrically charged field is accelerated through a
series of wave guides in conjunction with a radiofrequency pulse
to within a fraction of the speed of light. This electron beam can
itself be used for treatment or can impact on a target to produce a
photon beam of maximum energy between 4 and 20MV
according to the design and calibration of the machine.
• Usually given 5 days a week, for about 5 to 8 weeks.
• Electron beams can treat to depths
of up to 5 cm or so according to the
beam energy used; a 4–6MeV beam
would be mostly used to treat skin
tumours & a beam of approx. 12MeV
to treat neck nodes

17. Fractionation
• It is a technique of administering radiation therapy
in fractions instead of in a single high dose.
• Principle :- High total dose can be delivered to the
tumor while sparing adjacent normal tissue.
• Conventional schedule 80 to 200 cGy per
fraction, one fraction per day, 5 days per week for 6
to 7 weeks for a total dosage of 6500 to 7000 cGy.
• It depends on (1) Tissue response
(2) Duration of treatment
(3) Fraction size & number.

18. Effect consists of four independent processes :
(a) Repair of sublethal cellular damage
(b) Redistribution of tumor cells from radio-resistant (late S phase) into
radio-sensitive (G2-M) portions of the cell cycle
(c) Reoxygenation of the hypoxic (and hence radio resistant) portions of
tumors
(d) migration of normal cells into irradiated areas to repopulate these
normal tissues with healthy cells.
• Goal  To improve the therapeutic ratio by maximizing the
tumoricidal effect and minimizing acute & late toxicities while using
readily available low LET radiation.
• Three major categories of altered fractionation schemes are :-
1) Hyperfractionation,
2) Accelerated fractionation, &
3) Hypofractionation

19. 1) Hyperfractionation :- Improves the therapeutic ratio
primarily through
(1) redistribution of tumor cells into more
radiosensitive phases as a result of multiple fractions
(2) differential sparing of late-responding normal
tissues because of a decrease in the size of the dose per
fraction.
• Involves use of smaller fractions (i.e.<1.8Gy).
• The use of smaller fractions Reduce the risk of late
damage for a given total dose, but the increase in the
overall treatment time tends to reduce thE
effectiveness of treatment,

20. • Accelerated fractionations :- The overall treatment
time has been shortened.
• A greater benefit obtained from combining acceleration
with hyperfractionation & treating two or three times each
day.
• It reduced risk of normal tissue damage with the benefits of
completing treatment in a shorter overall time.
• Min. 6 hr interval between fractions is preferable repair of
sublethal damage.
• A good e.g. is the CHART regime (continuous
hyperfractionated accelerated radiotherapy)  RT at 1.5Gy
per fraction is given 3 times daily & continuously for 12
days to a total dose of 54Gy (i.e. without a weekend break).

21. • Hypofractionation :- It is the administration of high
dose per fraction (HDPF) radiation, in which only
one or two fractions are given per week.
• Mainly used for radioresistant tumors.
• It delivers higher doses of radiation per fraction (600
cGy twice a week or 800 cGy once weekly)
• Aim  To overcome the reparative capacity of the
tumor cells by increasing the damage per fraction.
SPLIT COURSE
• To prevent mucosal reaction, the radiotherapy
course is divided in two halves, seperated by a gap
of about 2 weeks.
• This allows the mucosal reaction to settle down

22. B] Brachytherapy (Internal radiation therapy)
• The radiation sources are placed either adjacent to the surface of a
tumor mass or bed or inside the tumor itself.
• Types :-a) Interstitial & b)Intra cavitary radiation
• Agents :-a) Permanent Radium, Caesium, Iridium
b) Temporary Radon, Gold, Iodine.
• Methods of implantation:- a) Radium & cesium In needle,
b) Iridium In wire form, c) Iodine & Gold As seeds & grains.
Iridium (Ir-192) wire > I-125 is the source of choice in HNC.
• Travels only a short distance to the desired target region, & its dose
intensity falls off rapidly with distance according to the inverse square
law.
• It permits sharp decrease in the dosage to the surrounding normal
tissue Radiation dose is delivered to a relatively small, well-defined
volume.

23. Low-dose rate (LDR) brachytherapy
• Delivers continuous radiation @ 40-200 cGy/hr.
• Likened to fractionated radiation with an infinite
number of small individual doses Allows
redistribution of the tumor cell within the cell cycle,
resulting in a greater % of malignant cells in the more
radiosensitive phase.
• Allows time for reoxygenation of hypoxic cells during
the treatment & thus results in an increase in their
radiosensitivity
• Favors late-responding normal tissues relative to
tumors, and repopulation does occur, but unfortunately ,
it benefits tumors more than normal tissues.

24. High-dose rate (HDR) brachytherapy
• Delivers radiation excess of 1200 cGy per hour.
• Have a higher risk for complications involving late
responding tissues.
• Therefore, it needs to be well fractionated to deliver only 1-
3 fractions/week.
Advantage of brachytherapy
a) It provides a means of delivering a high dose to a small
area & as the radiation dose falls off rapidly outside the
treatment volume, the dose to adjacent normal tissues can
be kept within acceptable limits
b) Head and neck tumor sites commonly considered suitable
for brachytherapy include the lip, floor of mouth, oral
tongue, base of tongue, buccal mucosa, tonsillar region,

25. a) Radiation at a distance from the source is min.
normal tissue damage is min.
b) Localised mucositis, filming on contralateral side
in case of parotid tumour is spared.
c) No Dryness of mouth.
d) Moist mouth & flexible tongue can be achieved in
early Ca tongue.
e) Used in cases of recurrance.
Limitations of brachytherapy
a) Need for adequate radiation protection and that the
technique is not appropriate where wider field
irradiation is required, for example to cover

26. IMMOBILISATION
a) Accuracy of delivery of EBRT is dependent on maintaining a
stable target volume.
b) Individually moulded thermoplastic shells covering the head and
neck area are used to immobilize patients.
c) These are located onto a fixed frame on the treatment couch.
d) Reference marks are placed on the outside of the shell, avoiding
the need for any skin marks or tattoos.
e) The areas around the eyes and mouth are cut out for patient
comfort and the part of the lower neck field to reduce the surface
dose.
f) Standard techniques allow T/t accuracy to within approx 3mm.
g) More rigid frames providing accuracy closer to 1–2mm have
been developed
for stereotactic radiotherapy & IMRT) where movement can be
more critical to dose delivery.

27. VOLUMES
• GTV = Gross tumor volume (gross disease) We can identify disease
extent
• CTV = Clinical target volume (subclinical disease)  we can predict
subclinical disease extent
• PTV = planning target volume (setup/treatment uncertainty)  we
know our precision and accurac
• IM = Internal margin  variations in size, shape, & position of the
CTV in reference to the patient's coordinate system using anatomical
reference points
• ITV = Internal target volume = CTV + IM
Alternative is an IGTV that can then be
expanded for CTV margins
• SM = Set‐up margin Uncertainties in pt.
beam positioning in reference to the T/t
machine coordinate system.

28. Actual area of delivery of radiation
PTV = GTV + CTV + Margin
PTV Pale blue area
Planning target volume = Gross Tumour Volume + Clinical
target volume + a margin around it to account for the
systematic and random errors plus physiological organ
changes that occur during the treatment planning and
delivery process.

29. Mechanism of action
• Rates of cellular proliferation of most tumours exceed that
of most normal tissues.
• In HNC, Potential doubling times (Tpot) range from 2 to 67
days (median 6.4 days).
• Cancer cells Generally less differentiated, More stem
cell-like, Reproduce more than most healthy differentiated
cells, & Have a diminished ability to repair sub-lethal
damage.
• Cells are most sensitive to radiation-induced damage during
the G2 and M phases of the cycle.
• After exposure to ionizing radiation, surviving cells undergo
partial synchronization as a consequence of G2 arrest,
which delays cells in a more radiosensitive phase.

30. • Malignant cells within the center of bulky tumors are
relatively hypoxic and therefore are relatively radioresistant
by virtue of the fact that they are more than 150 μm away
from a blood vessel, which is the maximum diffusing
distance of oxygen from a capillary
• Radiation therapy works by damaging the DNA of
cancerous cells.
• There is Direct damage to DNA of cancerous cells.
• Single-strand DNA damage is then passed on through cell
division; damage to the cancer cells' DNA accumulates,
causing them to die or reproduce more slowly.
• Generally, it takes up to 4–6 weeks after the end of a course
of radiotherapy for maximum tumour response to become
evident.

31. Basis of radiation energy
• The energy of diagnostic and therapeutic gamma- and X-rays is
expressed in kilovolts or megavolts (kV or MV).
• Energy of therapeutic electrons –Megaelectronvolts (MeV).
• 1 MV beam will produce photons of no more than about 1 MeV.
• X-rays are produced when electrons are accelerated to a high energy
• The mean X-ray energy is only about 1/3 of the maximum energy.
• Beam quality and hardness may be improved by special filters,
which improve the homogeneity of the X-ray spectrum.
• Bragg peak - The dose increases while the particle penetrates the
tissue, up to a maximum (the Bragg peak) that occurs near the end of
the particle's range & it then drops to
(almost) zero.
• The advantage of this energy deposition
profile is that less energy is deposited into
the healthy tissue surrounding target tissue.

32. Some examples of X-ray
energies used in medicine
• Diagnostic X-rays – 20 to 150 kV
• Superficial X-rays – 50 to 200 kV
• Orthovoltage X-rays – 200 to 500 kV
• Supervoltage X-rays – 500 to 1000 kV
• Megavoltage X-rays – 1 to 25 MV
Megavoltage X-rays are by far most common in
radiotherapy. Orthovoltage X-rays do have
limited applications, and the other energy ranges
are not typically used clinically

33. A] Orthovoltage radiotherapy: 200-500 kv
• Maximum dose is deposited at the skin surface and
dose falls to 90% at ~2 cm of depth in the tissue.
• Primarily suited for treatment of superficial tumors
that do not involve adjacent bone.
• Applications include primarily skin tumors, and
nasal cavity tumors after cytoreductive surgery.
relatively short source-to-skin distance (usually 50
cm) limiting the size of the treatment field
• Bone, cartilage necrosis is common  Osteoradio
necrosis, laryngeal cartilage necrosis.

34. 2] Supervoltage : 500 kV to 1 MV Most frequently
used in head and neck cancers Greater penetration
and skin sparing effect.
3] Megavoltage : Most frequently used.(1-4 MV)
• Machines – linnear accelerator.
Advantages :-
a) Greater penetration.
b) Absorbtion does not depend on atomic no.
c) Forward scatter effect - Incident skin recieves
smaller dose.
d) Homogenous beam distribution: no damage to
bone and cartilage.

35. • Brass Filters – thick end absorbs more radiation. So
used to turn the main axsis of the beam.
• 4 Mev and 10 MeV- Head and neck.
Disadvantages :-
a) Long distance machin
b) Beam does not arise from a point.- penumbra-
gamma rays

36. Special ways to deliver external
beam radiation
• Three-dimensional conformal radiation
therapy (3D-CRT)
• Intensity modulated radiation therapy
(IMRT)
• Image-guided radiation therapy (IGRT)
• Intensity modulated proton therapy (IMPT)
• Stereotactic radiosurgery (SRS) and
fractionated stereotactic radiotherapy
• Intraoperative radiation therapy (IORT)
• Electromagnetic-guided radiation therapy

37. Three-dimensional conformal radiation therapy
(3D-CRT)
• This technique uses imaging scan pictures and special computers
to map the location of a tumor very precisely in 3 dimensions.
• The patient is fitted with a plastic mold or cast to keep the body
part still during treatment.
• The radiation beams are matched to the shape of the tumor and
delivered to the tumor from several directions.
• Careful aiming of the radiation beam may help reduce radiation
damage to normal tissues and better fight the cancer by
increasing the radiation dose to the tumor.
• Photon beams or particles (like protons) can be used in this way.
• Drawback :- It can be hard to see the full extent of some tumors
on imaging tests, & any part not seen will not get treated with
this therapy.

39. 3D – CRT Images.
AXIAL VIEW SAGGITAL VIEW

40. Intensity-Modulated Radiation Therapy. (IMRT)
• High-precision radiotherapy that uses computer-controlled linear
accelerators to deliver precise radiation doses to a malignant tumor or
specific areas within the tumor.
• The intensity (strength) of the beams can be adjusted. This gives even
more control over the dose, decreasing the radiation reaching sensitive
normal tissues while delivering higher doses to the tumor
• A variation of IMRT is called volumetric modulated arc therapy. It uses
a machine (called RapidArc®).
• It delivers the radiation quickly as it rotates once around the body. This
allows each treatment to be given over just a few minutes. Although
this can be more convenient for the patient, it’s not yet clear if it’s more
effective than regular IMRT.
• A special cast or mold may be made to keep the body in place during
treatment. Again, miscalculations in tumor size and exact location can
mean missed areas will not get treated.
• Because IMRT uses a higher total dose of radiation, it may slightly
increase the risk of second cancers later on.

41. • The drawback with FPMS is that optimization is done using manual
iteration (trial and error) by the planning dosimetrist or physicist.
• With proper placement and weighting of beam angles, the number of
iterations can be significantly reduced.
• Treatment with IMRT is slightly longer that with 3DCRT, but
generally produces
• IMRT allows for the radiation dose to conform more precisely to the
three-dimensional (3-D) shape of the tumor by modulating—or
controlling—the intensity of the radiation beam in multiple small
volumes.
• IMRT also improves the ability to conform the treatment volume to
concave tumor shapes for example when the tumor is wrapped around
a vulnerable structure such as the spinal cord or a major organ or
blood vessel.
• IMRT also allows higher radiation doses to be focused to regions
within the tumor while minimizing the dose to surrounding normal
critical structures.

42. Preoperative Radiation Therapy
• Dose of approx. 5000 cGy using conventional fractionation of 180
-200 cGy / fraction is delivered 5 days / week for a total of up to 5
weeks.
• A 4-6 week period of rest is allowed for the patient to recover and
the acute inflammatory reaction to subside before surgical excision.
Advantages
• No treatment-related delay in surgery, limitations to the dose of
radiation, local and/or regional control
• Allows complete surgical, HP & biological evaluation of the tumor
& LN.
• Reduces tumour bulk, Oxygenation to tissues adequate.
• Lymphatics are blocked by radiation so dissemination of tumour is
less.
• Eliminates microscopic spread beyond palpable tumour mass

43. Disadvantages
a) Potential for delay in initiation of radiation therapy
if recovery from surgery is complicated flap
necrosis or fistula formation or other wound
problems
b) Scarring and vascular modifications from surgery
may decrease tissue
c) Oxygenation and thus adversely affect radiation
tumor cell kill.
d) Reduces vitality of tissues thus delays healing.

44. Postoperative Radiation Therapy
• It is indicated when the estimated risk of local-regional recurrence
of disease is <=20%.
• It should be initiated within 6 weeks of surgery to maximize the
benefits.
• PORT dose for the primary tumor site &/or the neck region using
conventional fractionation consists of a 180 - 200 cGy fraction/day
administered 5 days/wk up to a total dose of 6000 - 6300 cGy for
high-risk areas & 5000 - 5400 cGy for elective nodal irradiation.
Indications
a) Primary tumor factors :-Locally advanced T3 or T4 lesions, High-
grade histology, Presence of perineural or vascular invasion,
Concern with respect to the adequacy of the procedure irrespective
of the histological status of the surgical margins, Infiltrating rather
than pushing borders of the tumor, Positive or close margins of
surgical resection

45. a) Cervical nodal factors :- N stage higher than N1, Surgical
contamination (e.g., excisional or incisional biopsy) prior to
definitive surgery, Presence of gross extracapsular extension
Advantages
a) No treatment-related delay in surgery ,No limitations to radiation.
b) Allows complete surgical, histopathological and biological
evaluation of the tumor and lymph nodes
c) Residual microscopic disease can be effectively sterilized with
improved local and/or regional control
d) More effective bulk of mass removed, post op healing better
e) Extent of tumour is known so radiation given to suspected area.
Disadvantages
a) Potential for delay in initiation of radiation therapy if recovery
from surgery is complicated by fistula or other wound problems
b) Scarring & vascular modifications from surgery may decrease
tissue oxygenation & adversely affect radiation tumor cell kill.

46. Sandwich radiation therapy
• Preoperative RT followed by surgery, which is
followed by postoperative RT.
• A type of split course irradiation with a break in the
irradiation during which the surgery is performed.
• The major objective of this sequence is the
opportunity it provides for a rapid regeneration of
carcinoma during postop. recorative phase.

47. Reirradiation
• It is considered if adequate salvage surgery is not feasible or
if concerns exist about margins after salvage surgery.
• The important factors that have an impact on the feasibility
of reirradiation are (1) previous dose, volume, & tumor
response, (2) tolerance of normal tissues to additional
radiation, (3) radiation dose to adjacent vital structures, (4)
the feasibility of delivering a tumoricidal additional dose of
radiation, & (5) the need for bringing in nonirradiated
vascularized tissue to protect vital structures.
• One frequently encountered situation is recurrent metastatic
disease in a previously irradiated neck requiring salvage
neck dissection.
• In this setting, tumor invasion of the carotid sheath is quite
common.

48. RADICAL & PALLIATIVE RADIOTHERAPY
• Radical RT:- Used for highly radiosensitive tumors such as sq. cell ca.
of the nasopharynx & oropharynx, early-staged ca.larynx, Basal cell
carcinomas & superficial sq. cell ca of skin.
• In most instances, therapeutic doses of radiation > 6000 cGy and may
be >7000 cGy depending on them site, histology, and stage of the
tumor.
• Palliative RT:- Rt is an effective means of palliation of symptoms in
patients with incurable HNC.
• USES:- 1) Control of pain due to tumor shrinkage or necrosis by
relieving pressure on neural structures. 2) Lesions that obstruct the
airway can be palliated effectively when tumor shrinkage is achieved
with RT. 3) Control of hemorrhage from bleeding tumors
• Dose in the range of 4000 cGy usually is used for palliation.
Radical RT should commence within 4 weeks of the
decision to treat & Palliative RT within 2 weeks.

49. FACTORS INFLUENCING THE EFFECTIVENESS
OF RADIOTHERAPY
• Total dose.
• Concurrent treatment with chemotherapy or biological
agents
• Delays in starting treatment Has a relative risk of
locoregional recurrence of 1.15/month of delay for
radiotherapy as primary treatment & 1.28 for postop T/t.
• Treatment interruptions Local control falls by 1.4 % per
extra day when it is prolonged.
• Anaemia Hb should be>=12g/dL. Loss of local control of
disease by approx. 10–15 % for a 2 g/dL fall in Hb.
• Smoking Reduces T/t effectiveness by inhaled CO
displacing oxygen from Hb.

50. HNC : a) Laryngeal cancers.
Immobilization:- For all ca. larynx, patients should be
in the supine position with the cervical spine straight.
GLOTTIC CANCER
a) Most stage T1/T2,N0 –radical radiotherapy with surgery reserved for
salvage after radiotherapy fails
b) Local control rate- T1-90%, T2-70 -80%
c) Given through irradiation as it preserves natural voice and avoids
tracheostomy
For T1,
Ant- Field border should be in air,
Post-Anterior part of vertebral body
Sup- Lower border of hyoid bone
Inf- lower border of cricoid cartilage
Radiotherapy
for a T1/T2
N0 carcinoma
of the
glottis.

51. • FOR T2- depends upon its supraglottic and
subglottic extension
• Elective nodal irradiation is not needed as there is
extremely low incedence of cervical metastasis
• Dose depending upon field size by 5 fraction/week
a) -<36 cm2- 50 Gy in 16 fraction
b) 36 -42 cm2-55 Gy in 20 fraction
c) >42 cm 2 -64-66 Gy in 2Gy per fraction

52. SUPRAGLOTTIC TUMOURS
• For T1/T2,N0 supraglottic tumor Rich in lymphaticshigher LN
metastasis rate Requires elective nodal irradiation
• Achieved through two-phase technique
• Phase I= Primary tumour, whole larynx, pre epiglottic space &
cervical lymph nodes b/l in levels Ib,II,III ant spinal cord.
• Phase II= primary tumour & larynx
• Total dose = 66–70Gy in 2Gy/fraction, treating daily, 5 fractions a
week, to macroscopic disease & 44–50Gy in 2Gy/fraction, treating
daily, 5 fractions a week, to microscopic disease;

53. Subglottic tumors
• Subglottic tumours are rare present with locally advanced disease
requiring surgery followed by adjuvant RT. However, for patients with
early-stage disease,
• Incidence of cervical LN metastases is rare, involvement of
paratracheal nodes is estimated at 50 per cent, & treated electively.
• The radiation portal should extend from the top of the thyroid cartilage
sup. to the mid-trachea inf.
• This requires the use of either an ant oblique
beam arrangement or a coronal tech.in order that
good coverage of the inf. most area is achieved.
• Dose prescription:- total dose is 66–70Gy
in 2Gy per fraction, treating daily,5 fractions a wk,
to macroscopic disease & 44–50Gy in
2Gy per fraction, treating daily,
5 fractions a wk, to microscopic disease

54. Oropharygeal tumours (tonsil, tongue base, soft patate, PPW)
• Small T1/T2,N0 total dose is 66–70Gy in 2Gy/fraction, treating
daily, 5 fractions a wk, to macroscopic disease & 44–50Gy in 2Gy per
fraction, treating daily, 5 fractions a wk, to microscopic disease.
• Immobilization is in the supine position with the cervical spine
straight.
• Radiotherapy technique using parallel opposed feilds

55. Hypopharyngeal tumours (Pyriform fossa ,Postcricoid
region,PPW)
• Have high incidence of nodal metastases with submucosal spread
Elective nodal irradiation is necessary.
• Ca. hypopharynx have a tendency to present with locally advanced
disease Treated with radical chemoradiation.
• Immobilization: supine position with the cervical spine straight.
• Pyriform fossa: Target volume includes the primary tumour & levels
Ib–V LN B/l.
• Postcricoid region, PPW: CTV includes the primary tumour with a 2
cm (PPW) or 5 cm (post-cricoid) margin craniocaudally & levels Ib–V
LN B/l.
• Total dose: 66–70Gy in 2Gy/fraction,
treating daily, 5 fractions a wk, to macroscopic disease & 44–50Gy in
2Gy per fraction, treating daily, 5 fractions a wk,
to microscopic disease.

56. NASAL CAVITY
• Best treated with a combination of surgery with radiation and/or
chemotherapy.
• Definitive radiation for occasional early tumour.
• It may also be offered for advanced unresectable disease, although 5 yr
survival rates for the latter do not usually exceed 10 %.
• Advanced lesions  Radical radiation by using altered fractionation regime.
NASAL COLUMELLA / VESTIBULE
• Radiation is often undertaken in the first instance to avoid deformity.
• Small lessions may be treated with appositional electrons, with the CTV including
the primary tumour with a 2 cm margin.
• With more locally advanced lesions, CT planning is recommended, with the CTV
including the primary tumour with a 1 cm margin & the entire nasal septum.
• Dose prescription
• 1) For small lesions confined to the columella or vestibule = 55Gy in
20 fractions, treating daily, five times a week and
• 2) For more advanced lesions, with extension up the nasal
septum/cavity = 66–70Gy in 2Gy per fraction, treating daily, five times a week.

57. MAXILLARY SINUS
• Immobilization Supine position with the cervical spine straight & a
mouth bite in place to exclude the tongue & lower part of the oral
cavity from the radiation field.
• CTV maxillary sinus,ethmoid sinus,nasal cavity, pterygoid fossa &
lateral pharyngeal node Achieved using a heavily weighted anterior
field in combination with 1-2 lateral fields.
• Total dose 66–70Gy in 2Gy per fraction, treating daily, five
fractions a week.
Anterior field Lateral field

58. ETHMOID SINUS
• Immobilisation & total dose same as maxillary sinus.
• CTVBoth ethmoid sinuses,nasal cavity,
medial half of the maxilla on the I/L side
& pterygoid fossa.
• A 3 field plan,using a heavily weighted
2 ant. field & lat. fields achieves the best dose homogeneity.
ORAL CAVITY
• Best treated with surgery, followed by adjuvant radiation with or without
chemotherapy.
• Small (T1/T2), superficial (<5mm thickness) lesions of the oral tongue &
floor of mouth should be considered for interstitial brachytherapy.
• Oral tongue :- a) Small superficial lesions may be treated with interstitial
brachytherapy. (2-3iridium-192 hairpins). b)The CTV includes the primary
lesion with a 1 cm margin. c) The dose prescription for interstitial
brachytherapy = 60Gy over 6 days with iridium-192 LDR.
• Buccal mucosa, alveolus & small hard palate tumours These sites are

59. Complications HNC radiotherapy
Early
1) Fatigue, hair loss, Radiation
sickness.
2) Mucositis, loss of taste,
xerostomia.
3) Dryness of mucous
membranes.
4) Skin reaction(erythema, dry or
wet desquamation).
5) Candida infection.
6) Haematopoietic suppression.
7) Acute transverse mylitis.
Late
1) Permanent xerostomia.
2) Skin changes(atrophy of skin &
fibrosis).
3) Decaying of teeth.
4) Osteoradionecrosis.
5) Trismus, pharyngeal stenosis
6) Transverse myelitis, carotid artery
stenosis.
7) Radiation retinopathy, cataract.
8) Hypothyroidism, hypopitutarisim,
9) Radiation induced malignancy-
thyroid cancer, osteosarcoma of
orbit.
10) Carotid blowout syndrome.
11) Oropharyngocutaneous fistula.

60. Precautions that has to be taken….
During RT
1) Maintenance of good oral
hygiene.
2) Eat balanced & healthy diet.
3) Brushing 2-4 times daily with
soft-bristled brush.
4) Flossing daily Daily topical
fluoride Custom trays,
5) Brush-on prescription-strength
fluoride
6) Frequent saline rinses, lip
moisturizer (non-petroleum
based)
7) Passive jaw Opening
exercises to reduce trismus
Just After RT
• Complete dental work that was
deferred during radiotherapy
• Maintain integrity of teeth
especially those in radiation
fields
• Frequent follow-up

61. CYBERKNIFE
• Frameless robotic radiosurgical device that has been developed to treat
mainly extracranial lesions.
• The two main elements of the CyberKnife are :
(1) The radiation produced from a small linear particle accelerator.
(2) A robotic arm which allows the energy to be directed at any part of the
body from any direction.
• To correct for patient misalignment, the device provides both translational as
well as rotational corrections.
• RapidArc allows for very fast treatment. CK allows for very accurate
treatment.
• The robotic mounting allows very fast repositioning of the source, which
enables the system to deliver radiation from many different directions
without the need to move both the patient and source as required by current
gantry configurations.
• This imaging system allows the CyberKnife to deliver radiation with an
accuracy of 0.5mm. Uses 6D reconstruction.
• Corrections are made for the 3 translational motions (X,Y and Z) and three

62. PARTS

63. GAMMAKNIFE
• One of the most widely known stereotactic radiosurgery systems.
• Radiosurgery is a neurosurgical procedure whereby radiation is
delivered using stereotactic principles.
• The GammaKnife system uses 201 Cobalt-60 sources located in a
ring around a central treatment point ("isocenter").
• The Gamma Knife system is equipped with a series of 4 collimators
of 4mm, 8mm, 12mm and 16mm diameter, and is capable of
submillimeter accuracies.
• The Gamma Knife system does however require a head frame to be
bolted onto the skull of the patient, and is only capable of treating
cranial lesions.
• As a result of frame placement, treatment with Gamma Knife does
not require real time imaging capability as the frame does not allow
movement during treatment

65. IMPANOVALIS

66. ADVANCED
BRACHYTHERAPY

67. Few tips that may help to manage HNC RT problems…..
• Avoid strong spices & coarse foods, such as raw vegetables, dry crackers,
and nuts.
• Do not eat or drink very hot or very cold foods or beverages.
• Do not smoke, chew tobacco, or drink alcohol – these can make mouth sores
worse.
• Stay away from sugary snacks.
• Ask doctor or nurse to recommend a good mouthwash.
• Rinse mouth with warm salt and soda water every 1 to 2 hours as needed.
• Sip cool drinks often throughout the day.
• Eat sugar-free candy or chew gum to help keep mouth moist.
• Moisten food with gravies & sauces to make it easier to eat.
• Ask doctor or nurse about medicines to help treat mouth sores & control
pain while eating.
• Clean teeth & gums with a very soft brush after meals & at least one other
time each day.
• Use fluoride toothpaste that contains no abrasives.

68. Radiopharmaceuticals
• Drugs that contain radioactive materials
called radioisotopes
• Travel to various parts of the body put out
radiation, mostly in the form of alpha and
beta particles
• Eg: Treatment of bone pain Strontium 89 ,samarium
153,Radium- 223
• Treatment of thyroid cancer: radioactive iodine (also
known as radioiodine or iodine 131)

69. Organ Normal tissue tolerance (2Gy/fraction)
Lens 6
Cornea 40
Retina 50
Optic nerve 50
Optic chaisma 50-55
Spinal cord 44-48
Brain stem 48-54
Parotid gland 30
Lacrimal gland 30

70. What’s new in radiation
therapy?....
• Hyperthermia is the use of heat to treat cancer
• Hyperbaric oxygen therapy - Helps to increase the
sensitivity of certain cancer types to radiation
• Radiosensitizers:- Oxygen, Metronidazole etc..
• Radioprotectors: Amifostine